Heterogeneous distribution of the precursor of type I and type III collagen and fibronectin in the rough endoplasmic reticulum of palatal mesenchymal cells of the mouse embryo cultured in ascorbate-depleted medium

Summary In order to examine the intracellular distribution of precursors of type I and type III collagen and fibronectin in the palatal mesenchymal (MEPM) cells of the mouse embryo cultured under ascorbate-deficient conditions, immuno-electron-microscopic studies were carried out by use of affinity purified antibodies for these proteins. MEPM cells were obtained from the palatal shelves of 14-day-old mouse fetuses and cultured for 3–7 days in medium, either with or without 50 ng/dish/day ascorbic acid. Results obtained were as follows: (1) Although the rough endoplasmic reticulum (rER) of MEPM cells cultured for 5 days in ascorbate-supplemented medium was flattened, that in cells cultured in ascorbate-deficient medium had a distended or vesicular appearance. (2) Vesicular or distended rER showed heterogeneous staining for both type I and type III collagen, namely, some parts of rER showed positive staining for both types of collagen, while others showed negative staining. (3) Both type I and type III collagen showed codistribution in the same vesicular rER. (4) Vesicular rER showed negative or very faint labelling for fibronectin. These results may suggest regional differences in the function of rER.     

Isolation of a brain peptide identical to the intestinal PHI (peptide HI)

The isolation of a brain peptide identical to the intestinal peptide PHI (peptide HI) is described. The peptide was isolated from porcine brain extract using a chemical assay method based on its C-terminal isoleucine amide structure. The complete amino acid sequence of the peptide was found to be: His-Ala-Asp-Gly-Val-Phe-Thr-Ser-Asp-Phe-Ser-Arg-Leu-Leu-Gly-Gln-Leu-Ser-Ala- Lys-Lys-Tyr-Leu-Glu-Ser-Leu-Ile-NH2. This sequence is identical to the intestinal peptide thus demonstrating PHI to be a brain-gut peptide. The role of PHI in the central nervous system as a neurotransmitter or neuromodulator is discussed.     

Na_2SO_3和NaHCO_3对叶绿体CF_1－ATPase活力作用的机制

Ｎａ２ＳＯ３对热－ＤＴＴ活化的游离ＣＦ１及类囊体膜上ＣＦ１－ＡＴＰａｓｅ活力均有显著的促进作用,ＮａＨＣＯ３亦有明显的促进作用。Ｎａ２ＳＯ３和ＮａＨＣＯ３的促进作用与它们解除Ｍｇ２＋的抑制作用有关。从ＮａＨＣＯ３和Ｎａ２ＳＯ３及它们与Ｍｇ２＋之间的竞争性关系,表明三者是结合在酶的同一部位上。Ｎａ２ＳＯ３可明显降低热－ＤＴＴ活化的游禹ＣＦ１－ＡＴＰａｓｅ催化反应的活化能,这可能与促进产物ＡＤＰ的释放有关。     

Light and electron microscopical study of Nosema eurytremae

A nuclear-polyhedrosis virus (NPV) of the silkworm, Bombyx mori, which forms an icosahedral inclusion body, was transmitted to larvae of the rice stem borer, Chilo suppressalis. Serial passages of Bombyx NPV in the alternate host by injecting the supernatant of diseased hemolymph produced inclusion bodies with cuboidal and other shapes that differed from the original shape formed in Bombyx. These different shapes increased with times of passages, and after the twelfth passage, only cuboidal inclusion bodies were formed. The icosahedral inclusion bodies in B. mori and the cuboidal inclusion bodies in C. suppressalis occluded singly enveloped virions of the same size (350 × 75 nm), but the cuboidal inclusion bodies contained only a few virions and a large number of membraneous spherical structures. The formation process of the cuboidal inclusion body differed from that of the icosahedral. At first, irregularly branched inclusion bodies containing “vacant” spaces appeared in the infected nuclei. The bodies grew larger with the deposition of protein in the spaces between the branches, and this was accompanied with the occlusion of a large number of membraneous structures formed in the vicinity of the inclusion bodies, which became cuboidal in shape.     

Membrane-integration Characteristics of Two ABC Transporters, CFTR and P-glycoprotein

To what extent do corresponding transmembrane helices in related integral membrane proteins have different membrane-insertion characteristics? Here, we compare, side-by-side, the membrane insertion characteristics of the 12 transmembrane helices in the adenosine triphosphate-binding cassette (ABC) transporters, P-glycoprotein (P-gp) and the cystic fibrosis transmembrane conductance regulator (CFTR). Our results show that 10 of the 12 CFTR transmembrane segments can insert independently into the ER membrane. In contrast, only three of the P-gp transmembrane segments are independently stable in the membrane, while the majority depend on the presence of neighboring loops and/or transmembrane segments for efficient insertion. Membrane-insertion characteristics can thus vary widely between related proteins.     

A novel homozygous 10 nucleotide deletion in BBS10 causes Bardet–Biedl syndrome in a Pakistani family

Bardet–Biedl Syndrome is a multisystem autosomal recessive disorder characterized by central obesity, polydactyly, hypogonadism, learning difficulties, rod-cone dystrophy and renal dysplasia. Bardet–Biedl Syndrome has a prevalence rate ranging from 1 in 100,000 to 1 in 160,000 births although there are communities where Bardet–Biedl Syndrome is found at a higher frequency due to consanguinity. We report here a Pakistani consanguineous family with two affected sons with typical clinical features of Bardet–Biedl Syndrome, in addition to abnormal liver functioning and bilateral basal ganglia calcification, the latter feature being typical of Fahr's disease. Homozygous regions obtained from SNP array depicted three known genes BBS10, BBS14 and BBS2. Bidirectional sequencing of all coding exons by traditional sequencing of all these three genes showed a homozygous deletion of 10 nucleotides (c.1958_1967del), in BBS10 in both affected brothers. The segregation analysis revealed that the parents, paternal grandfather, maternal grandmother and an unaffected sister were heterozygous for the deletion. Such a large deletion in BBS10 has not been reported previously in any population and is likely to be contributing to the phenotype of Bardet–Biedl Syndrome in this family.     

Burkholderia pseudomultivorans sp. nov., a novel Burkholderia cepacia complex species from human respiratory samples and the rhizosphere

Eleven Burkholderia cepacia-like isolates of human clinical and environmental origin were examined by a polyphasic approach including recA and 16S rRNA sequence analysis, multilocus sequence analysis (MLSA), DNA base content determination, fatty acid methyl ester analysis, and biochemical characterization. The results of this study demonstrate that these isolates represent a novel species within the B. cepacia complex (Bcc) for which we propose the name Burkholderia pseudomultivorans. The type strain is strain LMG 26883^T (=CCUG 62895^T). B. pseudomultivorans can be differentiated from other Bcc species by recA gene sequence analysis, MLSA, and several biochemical tests including growth at 42 °C, acidification of sucrose and adonitol, lysine decarboxylase and β-galactosidase activity, and esculin hydrolysis.     

Role of phosphorylation on the structural dynamics and function of types III and IV intermediate filaments

Phosphorylation of types III and IV intermediate filaments (IFs) is known to regulate their organization and function. Phosphorylation of the amino-terminal head domain sites on types III and IV IF proteins plays a key role in the assembly/disassembly of IF subunits into 10 nm filaments, and influences the phosphorylation of sites on the carboxyl-terminal tail domain. These phosphorylation events are largely under the control of second messenger-dependent protein kinases and provide the cells a mechanism to reorganize the IFs in response to the changes in second messenger levels. In mitotic cells, Cdk1, Rho kinase, PAK1 and Aurora-B kinase are believed to regulate vimentin and glial fibrillary acidic protein phosphorylation in a spatio-temporal manner. In neurons, the carboxyl-terminal tail domains of the NF-M and NF-H subunits of heteropolymeric neurofilaments (NFs) are highly phosphorylated by proline-directed protein kinases. The phosphorylation of carboxyl-terminal tail domains of NFs has been suspected to play roles in forming cross-bridges between NFs and microtubules, slowing axonal transport and promoting their integration into cytoskeleton lattice and, in doing so, to control axonal caliber and stabilize the axon. The role of IF phosphorylation in disease pathobiology is discussed.     

Interleukin-13 interferes with CFTR and AQP5 expression and localization during human airway epithelial cell differentiation

Interleukin-13 (IL-13) is a central regulator of Th2-dominated respiratory disorders such as asthma. Lesions of the airway epithelial barrier frequently observed in chronic respiratory inflammatory diseases are repaired through proliferation, migration and differentiation of epithelial cells. Our work is focused on the effects of IL-13 in human cellular models of airway epithelial cell regeneration. We have previously shown that IL-13 altered epithelial cell polarity during mucociliary differentiation of human nasal epithelial cells. In particular, the cytokine inhibited ezrin expression and interfered with its apical localization during epithelial cell differentiation in vitro. Here we show that CFTR expression is enhanced in the presence of the cytokine, that two additional CFTR protein isoforms are expressed in IL-13-treated cells and that part of the protein is retained within the endoplasmic reticulum. We further show that aquaporin 5 expression, a water channel localized within the apical membrane of epithelial cells, is completely abolished in the presence of the cytokine. These results show that IL-13 interferes with ion and water channel expression and localization during epithelial regeneration and may thereby influence mucus composition and hydration.